The invention relates to a method for controlling the displacement motion of a part of a closure device that is driven by an electric motor in a motor vehicle.
Such methods are known from German Patent Publications DE 40 20 351 C2 and DE 197 45 597 A1. For recognizing a jamming incident at least one status value of the electric motor and/or of the closure device is compared with a characteristic value that defines a jamming incident. Status values for this purpose are, for example, the displacement force, the motor current, the r.p.m. or the torque moment of the motor. One could also think of detecting the positional change of the closure device or the speed thereof. The jamming incident is then defined by respective characteristic values, for example, a maximum displacement force, a maximum motor current, a minimum r.p.m. and so forth.
In this context, due to external influences, particularly the closing of vehicle doors and of other movable body parts, forces may be effective on the closure device, which forces oppose the displacement motion. Thus, the status values reach the characteristic values, if the forces have a corresponding strength, for a jamming incident thereby causing an emergency shut-off. The shut-off is characterized by a reversing, that is, an instantaneous opposite power supply to the motor which leads to an unmistakable backward motion of the moving part, frequently even into the completely open position thereof. While this cannot be avoided in an actual jamming incident for the protection of possibly pinched-in persons or body parts, a consumer could interpret this usually complete reversal as a failure function in the case that external influences caused the reaching of the comparing results which indicate a jamming incident.
Thus, German Patent Publication DE 40 20 351 C2 suggests sensing the acceleration forces acting on the vehicle body by a sensor and to take these forces into account as a base level. However, a detailed embodiment is not disclosed. If one takes into account the strength and dynamic of the acceleration forces acting on a vehicle body, it remains questionable whether and how such taking into account is technically realizable in a suitable manner.
On the other hand, German Patent Publication 197 45 597 A1 suggests controlling the displacement force of the motor as a sum of a force necessary for the displacement of the part and an adjustable excess force, whereby the displacement force and/or the excess force are controlled in closed loop fashion in response to the forces acting on the vehicle body. Even if one disregards the unclear determination of the force necessary for the displacement of the part and the effort and expense for an exact closed loop control of the displacement forces of the motor, the effort and expense for taking the external forces into account has proven itself to be substantial.
Alternatively, a variation of the displacement and/or excess force is controlled in closed loop fashion in response to opening and closing procedures of movable body parts in that the position of the movable body parts is ascertained by sensors and a variation. Particularly opening and closing procedures are recognized. In such a case an increase of the excess force or even discontinuing the pinching-in protection is suggested. Thus, however the pinching-in danger is put-up with. Additionally, this requires that the control device receives a signal from the sensors regarding the position change even prior to the occurrence of a pinching-in recognition.
Thus, it is an object of the invention to provide an alternative method for controlling the displacement motion of closure device, which method makes possible, on the one hand, a reliable and early recognition of a jamming incident and which, on the other hand, takes into account in a simple manner external influences by movable vehicle body parts.
The above object has been achieved by the present method for controlling a displacement motion of a movable part of a closure device in a motor vehicle. According to the invention the present method is characterized by the following steps:
(a) driving said movable part by an electric motor,
(b) determining at least one characteristic value that is significant for a jamming incident of said movable part,
(c) sensing at least one status value of at least one of said electric motor and said closure device wherein said at least one status value is also significant for said jamming incident,
(d) comparing said at least one status value with said at least one characteristic value for providing a jamming recognition signal,
(e) sensing a first position of at least one movable vehicle body member (e.g. door) to provide a first position signal,
(f) processing said jamming recognition signal and said position signal to provide a control signal,
(g) stopping said electric motor in response to said control signal for a predetermined length of stopping time (TStop), wherein said predetermined length of stopping time (TStop) begins at a beginning time (tx) when a jamming incident starts,
(h) determining, starting with said first position signal, whether a position change is taking place or has taken place within a predetermined time range (txxc2x1xcex94T) prior to or after the occurrence of said jamming recognition signal to provide a second position signal indicating a position change,
(i) continuing a displacement motion of said movable part in response to said second position signal, or
(j) assuming in the absence of said second position signal, the presence of a jamming incident and reversing said electric motor.
Thus, when a comparing result indicates that a jamming incident exists, the electric motor is stopped for a predetermined, short time duration, or alternatively, it is reversed. Thereby it is examined whether, within a given time range prior to and/or after the occurrence of a comparing result indicating a jamming incident and starting from a predetermined first position of the vehicle body part, a change of the position occurred and/or is occurring.
If within this time range the position signal indicates a change relative to the first position of a vehicle body part, the displacement motion in the closing direction is continued, otherwise a jamming incident is assumed to exist and the electric motor is reversed and/or the reversing is continued.
Thereby, the time duration may be determined corresponding to the reaction time of the sensor and the traveling time of the position signal up to the control to be so short that the customer does not notice this pause or the short time reversing during this time duration or at least it is not noticed as a disturbance. Particularly, time durations of about 150 to 100 msec or even shorter have been found to be sufficient to distinguish, by monitoring the sensors, between an actual jamming incident and an occurrence of comparable force caused by the closing of a vehicle body part, particularly the door. If one takes into account that the moved part including the mechanical components first have a substantial inertia and thus hardly come to an actual stop within a time duration of about 100 msec even if a reversing current is applied and additionally the time duration is too short with regard to the receptivity of the human eye, it becomes clear, that the customer will not notice even a reversing introduced for a short duration. On the other hand, the short duration stopping or the reversing have a critically higher safety in case of an actual jamming incident compared to the known alternatives of the prior art of a threshold increase or even a deactivation of the jamming protection.
A first further embodiment of the method is provided when a comparing result indicating a jamming incident and the first position of the vehicle body part are present simultaneously wherein first the electric motor is stopped or reversed again for the predetermined time duration and wherein the displacement motion is continued provided that within this time duration the position signal indicates a change of a vehicle body part relative to the first position. Thus, the case is covered in which the position signal arrives with such a delay, for example due to a slow data transmission, that the recognition has already responded in the case of respectively strong shock vibrations.
A second further development of the method is results, if starting from the given first position, a change of the position of the vehicle body part is recognized and if within a predetermined time range starting with this change, a comparing result occurs indicating a jamming incident. In this case the electric motor is also stopped for the predetermined time duration and the displacement motion is then continued, whereby the time duration of this stop does not need to be identical to that of the first further development, preferably it is clearly shorter. This further development thus covers the case wherein an already recognized door closing operation is immediately followed by a jamming incident.
The characteristic values for comparing with the status values which are significant for a jamming of a part, are adapted at a first position, particularly at an open position of a vehicle body part in a direction of a timewise later jamming recognition. An adaptation in the direction of a timewise later jamming recognition means for example an increase of the jamming characteristic value of the motor current or a reduction of the characteristic value of the r.p.m. and/or the displacement speed. Besides that, the characteristic values can be adapted for the comparing with the status values that are significant for the jamming of a part in response to the position and the motion direction of the movable part.
In a preferred manner the jamming recognition thus remains basically in an active state even after the end of the time duration of the stopping or of the reversing, if indicated, with relatively high characteristic values, so that a jamming incident occurring actually simultaneously with the closing of a door, is recognized even if the displacement is continued and a respective emergency shut-off is initiated.
The invention shall be explained in more detail in the following with reference to an example embodiment and the Figures.